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The LIAISON® 25 OH Vitamin D TOTAL Assay uses chemiluminescent immunoassay (CLIA) technology for the quantitative determination of 25-hydroxyvitamin D and other hydroxylated vitamin D metabolites in human serum to be used in the assessment of vitamin D sufficiency using the LIAISON® Analyzer family. Assay results should be used in conjunction with other clinical or laboratory data to assist the clinician in making individual patient management decisions in an adult population.

The LIAISON® 25 OH Vitamin D assay is a direct competitive chemiluminescence immunoassay (CLIA) for quantitative determination of total 25 OH vitamin D in serum. During the first incubation. 25 OH Vitamin D is dissociated from its binding protein and binds to the specific antibody on the solid phase. After 10 minutes the tracer, (vitamin D linked to an isoluminol derivative) is added. After a second10 minute incubation, the unbound material is removed with a wash cycle. Subsequently, the starter reagents are added to initiate a flash chemiluminescent reaction. The light signal is measured by a photomultiplier as relative light units (RLU) and is inversely proportional to the concentration of 25 OH vitamin D present in calibrators, controls, or samples.

The provided document describes the DiaSorin LIAISON® 25 OH Vitamin D TOTAL Assay, a chemiluminescent immunoassay for the quantitative determination of 25-hydroxyvitamin D in human serum. This is an in vitro diagnostic (IVD) device, and the acceptance criteria and study detailed are for its analytical performance, not for clinical diagnostic accuracy in the way a device like an AI for image analysis would be evaluated. As such, concepts like "experts to establish ground truth," "adjudication methods," "MRMC comparative effectiveness," and "standalone AI performance" are not directly applicable to this IVD assay and its performance evaluation. Ground truth in this context refers to established reference methods or known concentrations.

Here's an analysis based on the provided text, adapted for an IVD device:

1. Table of Acceptance Criteria (Inferred) and Reported Device Performance

The document doesn't explicitly state "acceptance criteria" as a table with predefined thresholds, but rather reports the performance characteristics observed in validation studies. The "acceptance criteria" are implied by what is considered acceptable performance for such an assay in the context of regulatory submission (e.g., meeting CLSI guidelines, demonstrating adequate precision, linearity, and minimal interference).

2. Sample Sizes and Data Provenance for Test Set (Validation Studies)

• Method Comparison: 587 samples.
  • Data Provenance: Samples were obtained from a clinical reference laboratory. The country of origin is not specified but given DiaSorin Inc.'s location in Minnesota, USA, and the FDA submission, it's likely primarily US data. It's retrospective (collected for testing).
• Reproducibility/Precision: A coded panel of 6 serum samples, plus 2 levels of kit controls. The exact number of replicates per sample/control at each site is not given, but it was a 20-day study.
  • Data Provenance: Samples prepared by DiaSorin Inc. (likely US). The study was performed at DiaSorin Inc. and 2 external sites.
• Dilution Linearity: Two (2) serum pools.
  • Data Provenance: Not explicitly stated, but likely laboratory-prepared serum pools.
• Functional Sensitivity: Samples prepared at nominal concentrations of 2.0 - 14.0 ng/mL.
  • Data Provenance: Not explicitly stated, but likely laboratory-prepared samples.
• Interfering Substances: Specific substances at various concentrations.
  • Data Provenance: Not explicitly stated, but likely laboratory-prepared samples or spiked samples.

3. Number of Experts and their Qualifications to Establish Ground Truth for the Test Set

This requirement is not applicable to this type of IVD device evaluation for analytical performance. The "ground truth" for analytical studies is established by:

• Using a well-established reference method (e.g., the predicate DiaSorin 25 OH Vitamin D RIA for method comparison).
• Using gravimetrically prepared or certified reference materials for precision, linearity, and functional sensitivity.
• Spiking experiments for interfering substances.

There are no human experts "adjudicating" diagnostic outputs in this context; it's a quantitative measurement device.

4. Adjudication Method for the Test Set

Not applicable. As described above, this is an analytical performance study, not a diagnostic accuracy study requiring adjudication.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was done

No. This is an automated immunoassay, not an AI-assisted diagnostic imaging device that involves human reader interpretation. Therefore, MRMC studies and "human readers improve with AI vs without AI assistance" are not relevant.

6. If a Standalone (algorithm only without human-in-the-loop performance) was done

Yes, the entire performance evaluation presented is a standalone (algorithm only) performance assessment, as it describes the analytical characteristics of the LIAISON® 25 OH Vitamin D TOTAL Assay system itself, without human interpretation as part of the primary result generation process. The device provides a quantitative number.

7. The Type of Ground Truth Used

• Method Comparison: The DiaSorin 25 OH Vitamin D RIA (a previously cleared predicate device) served as the comparative "ground truth" or reference method.
• Reproducibility/Precision: The known concentrations of the prepared serum samples and controls served as the reference for evaluating precision.
• Dilution Linearity: The expected concentrations based on dilution of known pools served as the reference.
• Functional Sensitivity: The known nominal concentrations of prepared samples were used.
• Interfering Substances: The known concentrations of added interfering substances were used to test their impact on the assay results.

8. The Sample Size for the Training Set

This is not applicable in the typical sense for this device. The LIAISON® 25 OH Vitamin D TOTAL Assay is a chemiluminescent immunoassay, not a machine learning or AI algorithm that undergoes "training" on a dataset in the way an AI model would. Its "training" is in the form of R&D and optimization of the assay reagents and protocols to achieve desired analytical performance. There isn't a "training set" of patient data for an algorithm.

9. How the Ground Truth for the Training Set was Established

Not applicable for the same reasons as (8). The assay's performance is optimized through traditional wet-lab biochemistry and immunoassay development, not algorithm training data.

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The DiaSorin LIAISON® 25 OH Vitamin D TOTAL Calibration Verifiers are assayed quality control materials intended for in vitro diagnostic use in the quantitative verification of calibration and reportable range of the LIAISON® 25 OH Vitamin D TOTAL Assay when performed on the LIAISON® Analyzer.

The LIAISON® 25 OH Vitamin D TOTAL Calibration Verifiers consist of four human serum-based total vitamin D levels with buffer salts and sodium azide. Each vial contains 5,0 mL of ready to use liquid material. The set is provided with targeted total vitamin D concentrations. The individual Calibration Verifier concentrations were chosen to represent values closest to the important decision limits used to determine Vitamin D sufficiency status in individual patients.

The LIAISON® 25 OH Vitamin D TOTAL Calibration Verifiers are assayed quality control materials intended for in vitro diagnostic use in the quantitative verification of calibration and reportable range of the LIAISON® 25 OH Vitamin D TOTAL Assay when performed on the LIAISON® Analyzer.

Here's an analysis of the acceptance criteria and the study performed:

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria are implicitly demonstrated by the "Expected Range" for each Calibration Verifier level. The reported device performance, in terms of precision (SD and %CV for overall results), falls within or is expected to enable the LIAISON® 25 OH Vitamin D TOTAL Assay to operate within these ranges.

The acceptance criteria are not explicitly stated for the device's own performance (e.g., maximum allowable %CV for a verifier), but rather the verifiers are designed to confirm the calibration and reportable range of the LIAISON® 25 OH Vitamin D TOTAL Assay. The study demonstrates the reproducibility of the verifiers themselves, indicating their stability and consistency for their intended use.

2. Sample Size Used for the Test Set and Data Provenance

• Sample Size: For each of the four Calibration Verifier levels (A, B, C, D) across three different lots, the sample size (N) for the precision study was 60. This was achieved by testing each verifier in quadruplicate, one run per day for 5 days, across 3 LIAISON® Analyzers (4 measurements/day * 5 days/run * 3 analyzers = 60).
• Data Provenance: The document does not specify the country of origin of the data. It is highly likely to be internal data from DiaSorin Inc., given the direct reference to their established performance and the conduct of the study to verify that performance. The study is prospective as it involves controlled testing under defined conditions specifically to assess the device's reproducibility.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications

This section is not applicable as the device is an assayed quality control material, not a diagnostic device that requires expert interpretation of results to establish ground truth. The "ground truth" for the Calibration Verifiers are their targeted total vitamin D concentrations, which would have been established by DiaSorin using a reference method or validated internal process during their manufacturing and assaying.

4. Adjudication Method for the Test Set

This section is not applicable. The study involves quantitative measurements by automated analyzers, not subjective assessments requiring adjudication among experts.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was done

No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not done. The device is a quality control material for an automated assay, not an imaging device or diagnostic tool requiring human interpretation. Therefore, there is no "human readers improve with AI vs without AI assistance" effect size to report.

6. If a Standalone (i.e. algorithm only without human-in-the loop performance) was done

Yes, a standalone performance study was done in the sense that the performance of the Calibration Verifiers was evaluated independent of human interpretation of results, using automated LIAISON® Analyzers. The focus was on the analytical reproducibility of the verifiers themselves when processed by the LIAISON® system.

7. The Type of Ground Truth Used

The ground truth for the Calibration Verifiers themselves is their "targeted total vitamin D concentrations" (as stated in the device description). These concentrations are established during the manufacturing and assaying of the control materials, likely using highly accurate reference methods or certified reference materials to assign the values.

8. The Sample Size for the Training Set

This section is not applicable. The LIAISON® 25 OH Vitamin D TOTAL Calibration Verifiers are quality control materials, not an artificial intelligence (AI) or machine learning (ML) algorithm that requires a training set. Their "targeted concentrations" are assigned through analytical processes, not learned from data.

9. How the Ground Truth for the Training Set was Established

This section is not applicable for the same reasons as #8.

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The LIAISON® 25 OH Vitamin D TOTAL Assay uses chemiluminescent immunoassay (CLIA) technology for the quantitative determination of 25-hydroxyvitamin D and other hydroxylated vitamin D metabolites in human serum, EDTA-plasma or lithium heparin plasma to be used in the assessment of vitamin D sufficiency. Assay results should be used in conjunction with other clinical or laboratory data to assist the clinician in making individual patient management decisions in an adult population.

The LIAISON® 25 OH Vitamin D TOTAL Control Set is intended for use as assayed quality control samples to monitor the accuracy and precision of the DiaSorin LIAISON® 25 OH Vitamin D TOTAL Assay.

The LIAISON® 25 OH Vitamin D TOTAL Specimen Diluent Set may be used to dilute specimens with values greater that 150 ng/mL by the LIAISON® 25 OH Vitamin D TOTAL Assay.

The LIAISON® 25 OH Vitamin D Assay (Cat. No. 310600) is an in vitro diagnostic device consisting of reagents provided in individual compartments within a plastic container called the Reagent Integral which allows for the performance of 100 determinations.

The LIAISON® 25 OH Vitamin D TOTAL Control Set (Cat. No. 310601) consists of two controls (2 vials each) provided in a separate box.

The LIAISON® 250H Vitamin D TOTAL Specimen Diluent Set (Cat. No. 310602) may be used to dilute specimens with values greater than 150 ng/mL.

Here's an analysis of the provided text regarding the acceptance criteria and the study that proves the device meets those criteria:

The provided text describes the LIAISON® 25 OH Vitamin D TOTAL Assay, a medical device for quantitatively determining 25-hydroxyvitamin D. The document outlines its intended use, a brief description of the device components, and performance data used to demonstrate its substantial equivalence to a predicate device.

1. Table of Acceptance Criteria and Reported Device Performance

The document does not explicitly state "acceptance criteria" for each performance metric as distinct pass/fail thresholds. Instead, it presents performance data from various studies. However, the implicit acceptance criterion for a 510(k) submission is that the device demonstrates comparable performance to a legally marketed predicate device. The "Conclusion" section explicitly states that the device is "substantially equivalent to the predicate assay."

• Serum Samples (Repeatability) - Serum Samples (Reproducibility)
• Plasma Samples (Repeatability) - Plasma Samples (Reproducibility) | Repeatability (within-assay variability): 2.9 to 5.5% CV (mean 7.7 to 128 ng/mL)
  Reproducibility (between-assay variability): 6.3 to 12.9% CV
  Repeatability (within-assay variability): 3.2 to 8.1% CV (mean 5.9 to 62.7 ng/mL)
  Reproducibility (between-assay variability): 6.9 to 12.7% CV | Precision (CV) comparable to the predicate device. |
  | Method Comparison | LIAISON = 0.99(RIA) + 2.4, R=0.97 (compared with a commercial radioimmunoassay product) | Strong correlation (R-value) and comparable results to the predicate device. |

2. Sample Size Used for the Test Set and Data Provenance

The document does not explicitly state the specific sample sizes for each performance test (e.g., how many individual serum or plasma samples were used for precision or method comparison).

• Linearity: "several serum specimens"
• Reproducibility/Precision: No specific numbers, only ranges of mean values (e.g., "over a range of mean values from 7.7 to 128 ng/mL").
• Method Comparison: No specific number for the “test set” of samples; a regression equation is provided.

Data Provenance: The document does not explicitly state the country of origin of the data or whether the studies were retrospective or prospective. It describes general laboratory performance evaluation studies.

3. Number of Experts Used to Establish Ground Truth and Qualifications

This information is not applicable to this type of device (an in vitro diagnostic immunoassay). The "ground truth" for an assay like this is typically established by reference methods or validated comparative methods, not by human experts interpreting images or complex clinical scenarios.

4. Adjudication Method for the Test Set

This is not applicable to this type of device. Adjudication methods (like 2+1 or 3+1) are common in studies where multiple human readers interpret medical images or clinical data and their interpretations need to be reconciled to establish a ground truth. For an immunoassay, the "ground truth" is derived from the result of the reference or comparative method.

5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study

This is not applicable. An MRMC study assesses human reader performance, often in interpreting images or making clinical diagnoses, sometimes with and without AI assistance. This device is an automated immunoassay and does not involve human readers for interpretation in the same way.

6. Standalone Performance Study (Algorithm Only Without Human-in-the-Loop)

Yes, the entire performance data presented (functional sensitivity, linearity, reproducibility/precision, method comparison) represents the standalone performance of the LIAISON® 25 OH Vitamin D TOTAL Assay. This assay is designed to operate without human "in-the-loop" decision-making regarding the assay results themselves, beyond standard laboratory quality control and result reporting. The device generates quantitative values directly.

7. Type of Ground Truth Used

The ground truth for demonstrating the performance of the LIAISON® 25 OH Vitamin D TOTAL Assay was primarily established by:

• Comparative Method: For the method comparison study, a "commercial radioimmunoassay product" was used as the comparator or "ground truth" against which the new device's results were evaluated. The linear regression analysis (LIAISON = 0.99(RIA) + 2.4, R=0.97) demonstrates the correlation with this established method.
• Internal Validation/Reference Methods: For other metrics like linearity and precision, the "ground truth" is derived from rigorous internal validation studies using well-characterized samples and established laboratory protocols (e.g., CLIA EP6-A for linearity).

8. Sample Size for the Training Set

This information is not applicable or not explicitly provided. Immunoassays like this are typically developed through biochemical and analytical optimization, not by "training" a machine learning algorithm on a "training set" of data in the same way an AI/ML device would be.

9. How the Ground Truth for the Training Set Was Established

As explained in point 8, the concept of a "training set" and "ground truth" for training is generally not applicable in the context of a traditional immunoassay device. The assay's analytical characteristics are established through chemical and biological principles and then validated through performance studies.

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